KoAbacus 1.0.53 - Korean Abacus & Mental Arithmetic The abacus is a calculating tool that was in use centuries before the adoption of the written modern numeral system and is still widely used by merchants, traders and clerks in Asia, Africa, and elsewhere. * button function 6,5,4,3,2,1 : - positional number + , - , x , / : the four arithmetical operation & new number genernation 9, 8, 7, 6, 5 : bounds stat & end : result * Menu Button - Auto Test : Count, Delay - Speech